Avian Metapneumovirus Infection Rhi ...

Avian Metapneumovirus Infection Rhinotracheitis (Swollen Head Syndrome SHD) in Laying Hens

Avian Metapneumovirus Infection Rhinotracheitis (Swollen Head Syndrome SHD) in Laying Hens

Happenings / Clinical Signs

Visibly sick birds

  • Few visibly sick birds
  • Usually less than 4% of the flock are affected

Egg drop

  • Egg production may be affected
  • Egg production drop gradually


  • Low mortality or increases gradually
  • Mortality rarely exceeds 2%

Dead Birds

  • Poor body fleshing condition

Head Comb Wattles Face Nostrils Sinuses Mount Beak Ear lobes

  • Swelling of the Head
  • Swelling of the periorbital and infraorbital sinuses


  • Respiratory signs spread fast
  • Widespread respiratory signs are usually present

Neurological /Nervous

As a result of secondary E. coli infection

  • Torticollis
  • Cerebral disorientation
  • Opisthotonus

Neck wings breast abdomen shanks legs hocks feet joints vent skin

  • Hens in lay may also present with prolapsed oviducts due to violent coughing

Shell quality

  • Pale or loss of colour in brown-shelled eggs
  • Misshapen eggs

The Avian metapneumovirus infection has been associated with swollen head syndrome (SHS) in chickens, which is characterized by the following clinical signs: swelling of the periorbital and infra-orbital sinuses, torticollis, cerebral disorientation and opisthotonus, as a result of secondary E coli infection. Usually less than 4% of the flock are affected, although, widespread respiratory signs are usually present. Mortality rarely exceeds 2%. The infection is associated with reduced egg production loss the shell colour and misshapen eggs.

Causing Agents
Avian metapneumovirus infection. Avian Metapneumoviruses are members of the subfamily Pneumoviridae, belonging to the family Paramixoviridae
Affected Systems/Organs
Respiratory, Reproductive and Neurological System
Transmission is rapid through aerosols via the respiratory route. Transmission from parents is uncertain. Contaminated objects.
Mainly Affects
Egg production, Egg quality and Liveability
Control respiratory stressors. Multivitamins. Good management practices. Good biosecurity.
Suggested Actions
  • Can be confirmed with clinical signs and gross lesions
  • Can be managed with feed additives, off-the-shelf medications
  • Diagnosis should be confirmed with rapid assays and/or a certified laboratory
  • Veterinary intervention is recommended

Impact on Egg quality


Impact on Liveability


Impact on Production


Overall Economic Impact


Y.M. Saif.2008.Disease of Poultry. 12th Edition. page 113

David E. Swayne. 2013.  Diseases of Poultry 13th Edition. page 115

Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition.

Paul McMullin. 2004. A pocket Guide to Poultry Health and Disease. First Edition.

Steven Leeson, John D. Summers. 2008. Commercial Poultry Nutrition. Third Edition.

Donald D. Bell, Williams D. Weaver. 2009.  Commercial Chicken Meat and Egg Production. Fifth Edition.

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